This application is based on and hereby claims priority to German Application No. 199358818.4 filed on Jul. 29, 1999, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The invention relates to an uncovering apparatus on a belt conveyor of a pick-and-place installation having a transporting belt loaded with pick-and-place elements and having a removal arrangement for removing pick-and-place elements. The invention also relates to a pick-and-place method using the uncovering apparatus.
2. Description of the Related Art
Pick-and-place arrangements with a transporting belt which has depressions in which pick-and-place elements are located are known. In order to prevent the pick-and-place elements from falling out of the depressions and to protect them against environmental influences, the depressions are covered by a flexible covering. This covering is drawn off at the start of the transporting belt in order that a removal arrangement can remove the pick-and-place element located in the first, uncovered depression. Following removal of the pick-and-place element by the removal arrangement, the transporting belt, with the sheet material secured, advances by one depression, with the result that, once again, a depression filled with a pick-and-place element is located beneath the removal arrangement and the next removal operation can begin. Following the removal of a certain number of pick-and-place elements, the removal arrangement moves to a further transporting belt in order to remove further pick-and-place elements there. Following completion of one or more further removal operations at one or more further transporting belts, the removal arrangement, finally, returns to the first transporting belt and the operation begins anew. The removal takes place, at each transporting belt, in a fixed position in each case. The transporting belt is moved at a displacement speed, as a result of which the depressions can be moved with adjustment accuracy to predetermined positions. In this case, the removal arrangement is far superior to the transporting belt in respect of adjustment accuracy and displacement speed.
Accordingly, the known pick-and-place arrangements have the disadvantage that the cycle time over which the pick-and-place elements can be removed from the depressions are limited by the transporting belt as the slowest link of the chain. A further reduction in the removal cycle time, which would be possible in principle on account of the quickness of the removal arrangement, cannot be achieved by the known uncovering apparatus.
The object of the present invention is thus to provide an uncovering apparatus for a belt conveyor of a pick-and-place installation which makes it possible for the cycle time of the removal of pick-and-place elements to be adapted to the dynamics of the removal arrangement.
The invention specifies an uncovering apparatus on a belt conveyor of a pick-and-place installation, it being the case that, in the pick-and-place installation, a transporting belt loaded with pick-and-place elements is provided with a flexible covering by which the pick-and-place elements are covered along a first longitudinal section of the transporting belt as far as a drawing-off position, and it being the case that the pick-and-place installation has a removal arrangement which can be displaced along the transporting belt and is intended for removing pick-and-place elements. The uncovering apparatus according to the invention, which is formed on a belt conveyor of the pick-and-place installation, has a rigid covering by which a plurality of pick-and-place elements are covered along a removal section of the transporting belt, which adjoins the drawing-off position directly, it being possible for the rigid covering to be displaced longitudinally in relation to the transporting belt by a plurality of pick-and-place element spacings, with the result that a number n of pick-and-place elements which corresponds to the plurality can be uncovered successively by the rigid covering.
For this purpose, the rigid covering is preferably designed such that it can be adjusted in a variable manner in length, for example telescopically. This makes it possible using the uncovering apparatus according to the invention, by adjustment of the length, for pick-and-place elements which are covered just by the rigid covering to be uncovered successively.
By virtue of some of the pick-and-place elements being covered according to the invention by a rigid covering, which may be coupled to the flexible covering, it is possible for the pick-and-place elements to be removed by the removal arrangement at different positions relative to the fixed transporting belt. The rigid covering here prevents the situation where the pick-and-place elements fall out of, or down from, the transporting belt prior to the removal by the removal arrangement. The removal of pick-and-place elements from different positions is made possible, furthermore, without the transporting belt being displaced, which is the time-critical factor. The possible coupling of the rigid covering to the flexible covering also makes it possible for pick-and-place elements to be uncovered alongside the displaceable rigid covering, and the rigid covering which can be adjusted in a variable manner in length, without the transporting belt being displaced.
A particularly advantageous uncovering apparatus on a belt conveyor of a pick-and-place installation is one in the case of which the pick-and-place elements are arranged in depressions of the transporting belt. As a result, by simply being positioned in the depressions, the pick-and-place elements may be fitted at defined spacings on the transporting belt without adhesives or the like being used.
A particularly advantageous realization of the coupling between the flexible and rigid coverings is one in the case of which, according to the invention, the rigid covering has a cutout through which the flexible covering is guided, at the drawing-off position, onto those sides of the rigid covering which are directed away from the transporting belt. Such a coupling can be realized particularly easily and cost-effectively.
Furthermore, it is particularly advantageous for the rigid covering to be coupled to a linear motor, which controls its movement and may be integrated, for example, in the covering, or a lifting magnet. Such a straightforward and cost-effective variant is fully sufficient for moving the rigid covering since this does not have to be displaced with the same accuracy as the transporting belt. For example, in the case of depressions in the transporting belt, the rigid covering need only ensure that the pick-and-place elements do not fall out of the depressions. Since the depressions are typically of a length corresponding to the length of the pick-and-place elements, a positioning accuracy for the rigid covering of approximately one third of the length of the depressions is sufficient. In contrast, in order to allow removal by the removal arrangement, it would be necessary for the transporting belt to be positioned with an accuracy of, for example, one tenth of the positioning accuracy of the rigid covering beneath the removal arrangement. The pick-and-place elements which are currently available have dimensions of not less than 0.1 mmxc3x970.1 mmxc3x970.2 mm, further miniaturization being expected.
It is particularly advantageous for the flexible covering to be configured as an adhesive sheet. Such an adhesive sheet prevents the pick-and-place elements from falling out and, at the same time, ensures adhesion of the flexible covering on the transporting belt and, possibly, on the pick-and-place elements.
The invention also specifies a pick-and-place method using the uncovering apparatus according to the invention, in the case of which the rigid covering first of all uncovers the pick-and-place element furthest away from the drawing-off position. Starting from the starting position in the removal section above the pick-and-place element uncovered by the rigid covering, the removal arrangement moves, in the direction of the drawing-off position, toward an end position. During this movement, the rigid covering successively uncovers a number comprising a total of n pick-and-place elements, as required for a pick-and-place cycle, which are removed by the removal arrangement.
In accordance with the advantageous uncovering apparatus on a belt conveyor of a pick-and-place installation having a transporting belt which has depressions, the method in the case of which the pick-and-place elements are removed from depressions of the transporting belt is also particularly advantageous.
Furthermore, in a cyclic method in the case of which the removal arrangement can only cover a limited distance along the transporting belt, it is particularly advantageous if, following removal of the nth pick-and-place element, the removal arrangement returns to the starting position and the transporting belt, together with the rigid and flexible coverings, is displaced by a corresponding amount in the same direction. Following the return of the removal arrangement to the first transporting belt, the removal process may then recommence.